A new study says federal guidelines on obesity should be revised so more women fit into the category of "obese."

U.S. guidelines determine who is obese based on body-mass index, a measurement of whether a person's height and weight are proportional. The researchers found that about half the women of reproductive age considered obese under World Health Organization guidelines -- which use body-fat analysis instead -- were not obese under federal guidelines.

Under the international guidelines, about half of white women and more than two-thirds of Latino women are considered obese.

"It is especially important to accurately assess obesity in reproductive-age women, as they are more likely to be obese than similarly aged men," study author Dr. Mahbubur Rahman, an assistant professor at the University of Texas Medical Branch's Department of Obstetrics and Gynecology, said in a news release from the school. "These women are at risk for cardiovascular disease, diabetes and other obesity-related health conditions, and may forgo or be overlooked for needed tests and treatments."

"BMI is not 'one size fits all.' Inaccurate classification can decrease the impact of obesity prevention programs that will result in many women not receiving the help they need," study senior author Dr. Abbey Berenson, director of the university's Center for Interdisciplinary Research in Women's Health, said in the news release.

The researchers predict that further studies will show similar results for men and other age groups.

The study appears online in the May issue of Obstetrics and Gynecology.